Basic of the Email marketing funnel:
Email marketing is a system of direct marketing that uses electronic mail as a means of communicate with an readers of commercial or fundraising messages. In its broadest sense, each email sent to a expected or current customer may be considered email marketing
These people to start spend more time on your website or reading your content and watching your content and they are starting to get interested in what your product could do for them some point they have to make decision. So they are deciding purchase or not. And hopefully you are helping them to make that decision reinforcing that you will solve them problem.
And then lastly they take action and they buy or not. And so the small part of the funnel are people who have actually taken action.
The goal is to work people through they entire funnel.